Safe: A JTextArea is a multi-line area that displays plain text.
It is intended to be a lightweight component that provides source
compatibility with the java.awt.TextArea class where it can
reasonably do so.
You can find information and examples of using all the text components in
Using Text Components,
a section in The Java Tutorial.

This component has capabilities not found in the
java.awt.TextArea class. The superclass should be
consulted for additional capabilities.
Alternative multi-line text classes with
more capabilities are JTextPane and JEditorPane.

The java.awt.TextArea internally handles scrolling.
JTextArea is different in that it doesn't manage scrolling,
but implements the swing Scrollable interface. This allows it
to be placed inside a JScrollPane if scrolling
behavior is desired, and used directly if scrolling is not desired.

The java.awt.TextArea has the ability to do line wrapping.
This was controlled by the horizontal scrolling policy. Since
scrolling is not done by JTextArea directly, backward
compatibility must be provided another way. JTextArea has
a bound property for line wrapping that controls whether or
not it will wrap lines. By default, the line wrapping property
is set to false (not wrapped).

java.awt.TextArea has two properties rows
and columns that are used to determine the preferred size.
JTextArea uses these properties to indicate the
preferred size of the viewport when placed inside a JScrollPane
to match the functionality provided by java.awt.TextArea.
JTextArea has a preferred size of what is needed to
display all of the text, so that it functions properly inside of
a JScrollPane. If the value for rows
or columns is equal to zero,
the preferred size along that axis is used for
the viewport preferred size along the same axis.

The java.awt.TextArea could be monitored for changes by adding
a TextListener for TextEvents.
In the JTextComponent based
components, changes are broadcasted from the model via a
DocumentEvent to DocumentListeners.
The DocumentEvent gives
the location of the change and the kind of change if desired.
The code fragment might look something like:

Warning:
Serialized objects of this class will not be compatible with
future Swing releases. The current serialization support is
appropriate for short term storage or RMI between applications running
the same version of Swing. As of 1.4, support for long term storage
of all JavaBeansTM
has been added to the java.beans package.
Please see java.beans.XMLEncoder.

getScrollableUnitIncrement(Rectangle visibleRect,
int orientation,
int direction)Enabled: Components that display logical rows or columns should compute
the scroll increment that will completely expose one new row
or column, depending on the value of orientation.

int

getTabSize()Enabled: Gets the number of characters used to expand tabs.

createDefaultModel

Creates the default implementation of the model
to be used at construction if one isn't explicitly
given. A new instance of PlainDocument is returned.

Returns:

the default document model

setTabSize

public void setTabSize(int size)

Enabled: Sets the number of characters to expand tabs to.
This will be multiplied by the maximum advance for
variable width fonts. A PropertyChange event ("tabSize") is fired
when the tab size changes.

getTabSize

Enabled: Gets the number of characters used to expand tabs. If the document is
null or doesn't have a tab setting, return a default of 8.

Returns:

the number of characters

setLineWrap

public void setLineWrap(boolean wrap)

Enabled: Sets the line-wrapping policy of the text area. If set
to true the lines will be wrapped if they are too long
to fit within the allocated width. If set to false,
the lines will always be unwrapped. A PropertyChange
event ("lineWrap") is fired when the policy is changed.
By default this property is false.

getLineWrap

public boolean getLineWrap()

Enabled: Gets the line-wrapping policy of the text area. If set
to true the lines will be wrapped if they are too long
to fit within the allocated width. If set to false,
the lines will always be unwrapped.

Returns:

if lines will be wrapped

setWrapStyleWord

public void setWrapStyleWord(boolean word)

Enabled: Sets the style of wrapping used if the text area is wrapping
lines. If set to true the lines will be wrapped at word
boundaries (whitespace) if they are too long
to fit within the allocated width. If set to false,
the lines will be wrapped at character boundaries.
By default this property is false.

getWrapStyleWord

public boolean getWrapStyleWord()

Enabled: Gets the style of wrapping used if the text area is wrapping
lines. If set to true the lines will be wrapped at word
boundaries (ie whitespace) if they are too long
to fit within the allocated width. If set to false,
the lines will be wrapped at character boundaries.

Returns:

if the wrap style should be word boundaries
instead of character boundaries

getColumnWidth

protected int getColumnWidth()

Gets column width.
The meaning of what a column is can be considered a fairly weak
notion for some fonts. This method is used to define the width
of a column. By default this is defined to be the width of the
character m for the font used. This method can be
redefined to be some alternative amount.

paramString

Returns a string representation of this JTextArea. This method
is intended to be used only for debugging purposes, and the
content and format of the returned string may vary between
implementations. The returned string may be empty but may not
be null.

getScrollableTracksViewportWidth

public boolean getScrollableTracksViewportWidth()

Enabled: Returns true if a viewport should always force the width of this
Scrollable to match the width of the viewport. This is implemented
to return true if the line wrapping policy is true, and false
if lines are not being wrapped.

getPreferredScrollableViewportSize

Enabled: Returns the preferred size of the viewport if this component
is embedded in a JScrollPane. This uses the desired column
and row settings if they have been set, otherwise the superclass
behavior is used.

getScrollableUnitIncrement

Enabled: Components that display logical rows or columns should compute
the scroll increment that will completely expose one new row
or column, depending on the value of orientation. This is implemented
to use the values returned by the getRowHeight and
getColumnWidth methods.

Scrolling containers, like JScrollPane, will use this method
each time the user requests a unit scroll.

getAccessibleContext

Suppressed: Gets the AccessibleContext associated with this JTextArea.
For JTextAreas, the AccessibleContext takes the form of an
AccessibleJTextArea.
A new AccessibleJTextArea instance is created if necessary.